Control arrangement for a printing system

ABSTRACT

A printing system for producing prints from a print job is provided. The printing system includes first and second digital fronts ends as well as an image path. The image path communicates selectively with the first digital front end and the second digital front end, and receives ( 1 ) printable information from the first digital front end when the first digital front end and the image path are configured in a first mode, and ( 2 ) printable information from the second digital front end when the second digital front end and the image path are configured in a second mode. A selection system disposes the first digital front end and the image path in the first mode, or the second digital front end and the image path in the second mode.

BACKGROUND AND SUMMARY

The disclosed embodiments relate to an improved control system for aprinting system and, more particularly, to a switchable digital frontend (DFE) implementation permitting multiple digital front ends to beselectively used with a single print engine.

Digital printing systems can be as simple as an office laser printer orcan be room size devices that include multiple paper feeders, multiplemark facilities (for example a black and white unit and a color unit),collators, staplers and shrink wrappers. Larger standalone systems, suchas the Xerox iGen3™ 110 Digital Production Press include an inputmodule, sometimes referred to as a “digital front end (DFE),” in whichvarious operations are performed on an incoming print job. An example ofa complex DFE, performing such operations as decomposition, imageprocessing, and image editing is described in U.S. Pat. No. 5,493,634,the pertinent portions of which are incorporated herein by reference.

It is known that large color publishing systems, such as the XeroxiGen3™ 110 Digital Production Press, can be configured with one ofseveral publicly available DFEs, and it is also known that certain DFEsare better suited for certain document processing applications thanothers. For example, it is understood that a first type of DFE might bepreferred for use in graphic arts applications, while a second type ofDFE might be preferred for use in applications other than graphic arts.As the use of large color publishing systems continues to expand,however, it is contemplated that a single shop or user might desire toemploy multiple DFEs for the purpose of providing graphic arts and otherapplications under the “same roof.”

There is a desire among graphic arts and standard color printingcustomers to use multiple DFEs with a single print engine (PE). Also,for field service training and trade shows, there is a demand todemonstrate more than one DFE with a single PE. As understood,alternating DFEs requires a service representative to manually swap DFEcards (and related components) in and out of a host printing system. Theswapping process can be time consuming, and the reliability of the hostprinting system can be jeopardized. In particular, over time, therepeated insertion and removal of image data interface cards (IDICs),along with associated interface connectors, can be harmful to thesystem. There are several risks associated with continued insertion,including: static discharge damage to the boards, damage to anassociated backplane due to disconnect connect cycles, and damage tofiber-optic or other interface cables. It would be desirable to providean arrangement in which multiple DFEs could be used alternately with asingle PE without the need to manipulate related hardware after initialinstallation.

In accordance with the one aspect of the disclosed embodiments, there isprovided a printing system for producing prints from a print job. Theprinting system includes: a first digital front end capable ofdecomposing the print job, a second digital front end capable ofdecomposing the print job and an image path. The image path, whichcommunicates selectively with the first digital front end and the seconddigital front end, receives a decomposed print job from the firstdigital front end when the first digital front end and the image pathare configured in a first mode, and receives a decomposed print job fromthe second digital front end when the second digital front end and theimage path are configured in a second mode. The printing system furtherincludes a selection system for disposing the first digital front endand the image path in the first mode, or the second digital front endand the image path in the second mode.

In accordance with another aspect of the disclosed embodiments, there isprovided a print control system for use with a print engine. The printcontrol system includes a first control subsystem for decomposing afirst job to obtain a first set of print-related information, and asecond control subsystem for decomposing a second job to obtain a secondset of print-related information. The print control system furtherincludes a switching system communicating with the first controlsubsystem and the second control system. In operation the switchingsystem is disposed in a first switching state at a first time to directthe first set of print-related information from the first controlsubsystem to the print engine, and is disposed in a second switchingstate at a second time to direct the second set of print-relatedinformation from the second control subsystem to the print engine.

In accordance with yet another aspect of the disclosed embodiments,there is provided a method for producing prints from a print job. Themethod includes: configuring a first digital front end, a second digitalfront end and image path in such a way that the image path receives arasterized print job from the first digital front end when the firstdigital front end and the image path are configured in a first mode, andthat the image path receives a rasterized print job from the seconddigital front end when the second digital front end and the image pathare configured in a second mode; and disposing either the first digitalfront end and the image path in the first mode, or the second digitalfront end and the image path in the second mode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic, elevational view of selected elements of axerographic color printing system;

FIG. 2 is a schematic, block diagrametric view of a monochrome printplatform including a digital front end communicating with selectedcomponents of an image path;

FIG. 3 is a schematic, block diagrametric view of a color print platformincluding a digital front end communicating with selected components ofan image path;

FIG. 4 is a schematic, block diagrametric view of a print platform witha switchable control arrangement;

FIG. 5 is a schematic elevational view of a switching network forselectively connecting multiple digital front ends to an image path; and

FIG. 6 is a schematic elevational view of an error detection circuit fordetecting errors that might arise in print platforms with multipledigital front ends, such as the print platform shown FIG. 4.

DETAILED DESCRIPTION

Referring to FIG. 1, there is shown a simplified elevational view ofseveral elements of an exemplary prior art color printing apparatus. Theexemplary color printing apparatus, designated by the numeral 8, employsan “image-on-image” xerographic technology in which successiveprimary-color images are accumulated on a photoreceptor belt, and theaccumulated superimposed images are in one step directly transferred toan output sheet as a full-color image. As will appear, other monochromeor color printing apparatuses, using xerographic or ink-jet basedtechnologies, would be suitable for use with the disclosed embodiments.

As shown in FIG. 1, the prior art printing apparatus 8 includes a beltphotoreceptor 10, along which are disposed a series of stations, as isgenerally familiar in the art of xerography, one set for each primarycolor to be printed. For instance, to place a cyan color separationimage on photoreceptor 10, there is used a charge corotron 12C, animaging laser 14C, and a development unit 16C. For successive colorseparations, there is provided equivalent elements 12M, 14M, 16M (formagenta), 12Y, 14Y, 16Y (for yellow), and 12K, 14K, 16K (for black). Thesuccessive color separations are built up in a superimposed manner onthe surface of photoreceptor 10, and then the combined full-color imageis transferred at transfer station 20 to an output sheet. The outputsheet is then passed through a fuser 30, as is familiar in xerography.It will be appreciated by those skilled in the art that signals of theimaging lasers 14C, 14M, 14K and 14Y are provided by “digital front end(DFE),” designated by the numeral 100. The image signals vary as afunction of image data accepted, stored, produced, decomposed orotherwise presented at the DFE1 100. Further platform related detailsregarding the DFE1 100 are provided in U.S. Pat. No. 6,718,878, thepertinent portions of which are incorporated herein by reference.

FIG. 2 illustrates a single “channel” for image data, such as would beused by itself in a monochrome printer, or as one channel among many,one channel for each primary color, in a full-color system. Although theoutput of the illustrated embodiment is the laser 14 such as describedabove, the disclosed embodiments relate to other image modulatingdevices, such as LED bars, LCD arrays, etc, or to other printingtechnologies, such as ink-jet, etc.

Referring still to FIG. 2, DFE1 100 accepts data for images desired tobe printed in any one of a number of possible formats, such as, forexample, HP PCL, or Adobe® PostScript™. This image data is then“interpreted” or “decomposed” in a known manner into a format usable bydownstream circuitry and software. The decomposed data is first appliedto an image data interface card (IDIC) 102; the output of IDIC 102 is,where required, “contone” (“continuous tone”) data concerning specificlocations, or pixels in the desired image. In general, contone data canbe defined as a scalar number (such as from 0 to 255) symbolic of thedesired darkness of the particular indicated area in the image. Thiscontone data is then sent to what is called a “contone renderingmodule,” or CRM, 104. As is known in the art, most currently-populardigital printing technologies, such as xerography and ink jet, are ineffect “binary” at the pixel level: any particular pixel can be onlyblack (or saturated in a color) or not-black (no color). In order toobtain a halftone or gray area, the contone data may be converted to ascreen or other “halftone” pattern, which, over an area slightly largerthan the pixel level, approximates the desired darkness. CRM 104performs this conversion. The output of CRM 104 is binary data which, byitself, is largely directly operative of hardware, such as to modulatean imaging laser or activate an ink-jet ejector within a printhead at aparticular time. The binary data from CRM 104 is typically passedthrough, in this case, a ROS (raster output scanner) interface module,or RIM, indicated as 106. The RIM reorganizes and synchronizes thebinary image data for synchronous delivery to the laser 14 incooperation with, for example, the motion of photoreceptor 10.

The basic image path elements described above may be controlled by amarker I/O processor, or MIOP, 110. MIOP 110 is connected to theelectronic circuitry (ASICS or printed circuit boards) forming CRM 104and RIM 106, with controlling, messaging, and data passing means, suchas through a VME32 bus 114; it in turn may receive instructions fromDFE1 100 by way of alternate communication channel 116.

The image path of FIG. 2 is, as previously mentioned, suitable for amonochrome printer, or for a single color separation in a full-colorprinter. In a color embodiment of the disclosed embodiments, there isprovided a plurality of such channels as shown in FIG. 2; animplementation of such a color version is shown in FIG. 3. As can beseen, the various elements shown in the image path of FIG. 2 arereplicated for each primary color; a single MIOP 110 can interact withthe DFE1 100 to coordinate activities of each image path.

Referring now to FIG. 4, a multiple DFE input system adapted for usewith a monochrome or color printing engine is designated by the numeral120. As shown in FIG. 4, DFE1 100 and DFE2 122 are selectively connectedwith “cards” IDIC1 102, IDIC2 124, CRM 104 and RIM 106 by way of aselection network 126. The selection network 126 communicates with aconventional user interface (UI), designated with the numeral 128, thesignificance of which will appear below. Also, as described above (andas described with respect to U.S. Pat. No. 6,526,240, the pertinentportions of which are incorporated herein by reference), the cardsoperate in a control platform or “card cage.” A few generalizationsabout the system of FIG. 4 follow:

-   -   In one example of operation, DFE1 100 may be predominately        suited for one application area (e.g., graphic arts application)        and DFE2 122 may be predominately suited for another application        area (e.g., standard color printing application).    -   The IDIC1 , IDIC2, CRM and RIM boards (“Boards”) share an image        data interface bus (e.g., a “JIDI bus” used in Xerox iGen3™ 110        Digital Production Press), designated by the numeral 130. Thus        the IDIC1, IDIC2 or RIM boards can selectively deliver images to        the bus 130. Also, consistent with the description above, one        set of Boards (or at least a partial set of Boards) is        preferably provided for each color separation. So for a CMYK        printing arrangement (See e.g., FIG. 3), each one of IDIC1,        IDIC2 and RIM would comprise a set of four boards.    -   The current card cage allows either the IDIC1, IDIC2 or the RIM        card to control the bus 130 based upon the status of two        mutually exclusive signals: Int_ImgReq′ (Internal Image Request)        and DFE_PageReq′ (DFE Page Request). In one mode of operation,        DFE_PageReq′ is the signal used to coordinate image data        transfer from either DFE1 100 to IDIC1 102 or DFE2 122 to IDIC2        124. More particularly, there is a “negotiation” across the DFE        PageReq lines to determine when IDIC1 or IDIC2 is ready to        receive print-related information from either DFE1 or DFE2. This        form of negotiation is currently used in configurations        including a DocuSP (“DocuSP” is a trademark used by Xerox        Corporation) DFE communicatively coupled with a Xerox iGen3™ 110        Digital Production Press.

Referring now to FIG. 5, the structure and operation of selectionnetwork 126 is described in further detail. In a CMYK example ofoperation, the request signal corresponding with the first separation(“ADFE_PageReq′”) is selectively transmitted to gates 132A and 132B, therequest signal corresponding with the second separation(“BDFE_PageReq′”) is selectively transmitted to gates 134A and 134B, therequest signal corresponding with the third separation (“CDFE_PageReq′”)is selectively transmitted to gates 13A6 and 136B, and the requestsignal corresponding with the fourth separation (“DDFE_PageReq′”) isselectively transmitted to gates 138A and 138B. Additionally, a firstselect signal (“IDIC2_Select” passed through inverters 140 and 142) isinput to gates 132B, 134B, 136B and 138B. Finally, a second selectsignal (inverted IDIC_Select passed through inverter 144), istransmitted to an error detection circuit 146 (FIG. 6), the significanceof which is discussed below.

It should be noted that while 4 sets of OR gates are shown for theimplementation of FIG. 5 (corresponding with a four separation printingsystem), more or less OR gates sets could be employed, depending on thenumber of separations required by an associated printer. Additionally,the disclosed logical devices of FIG. 5 could be implemented withalternative logical devices and/or through use of a programmable gatearray. Finally, the selection network 126 is provided with a manualselector 150, the significance of which will be described below.

Referring still to FIG. 5, in one exemplary form of operation, the firstselect signal is maintained as an active high. In this way PageReq1signals are output from gates 132A, 134A, 136A and 138A, while gates132B, 134B, 136B and 138B are maintained in a low state. That is, whenthe first select signal is high, DFE1 100 operates in conjunction withIDIC1 102 to provide the default control system for the printing system8, and DFE2 122 is maintained in an inactive state. To change thedefault control system, a user accesses the user interface 126 (FIG. 4)to change the state of the first select signal from a normal high to anactive low. In this way PageReq2 signals are then output from gates132B, 134B, 136B and 138B, while gates 132A, 134A, 136A and 138A aremaintained in a low state. That is, when the first select signal is anactive low, DFE2 122 operates in conjunction with IDIC2 124 to providethe default control system for the printing system 8, and DFE1 100 ismaintained in an inactive state.

In a slight variation of the above-described operation a user,preferably a service technician or the like, can change the state of thefirst select signal without employing a user interface. In particular,the service technician or the like can access the manual selector 150 tochange the state of the first select signal from high to active low, orvice versa.

Referring now to FIG. 6, the structure and operation of the errordetection circuit 146, in which a 2:1 multiplexer is provided for eachseparation, is described. For the exemplary arrangement of FIG. 5, fourmultiplexers, designated by the numerals 154A, 154B, 154C and 154D areprovided. It should be appreciated that more or less multiplexers couldbe employed, depending on the number of separations required by anassociated printer. In the exemplary configuration of FIG. 6, the secondselect signal (“GSelect2′”) is input to each one of the fourmultiplexers, and the state of the second select signal determines whichof the error signals (“AError1′” and AError2′” for multiplexer 154A;“BError1′” and BError2′” for multiplexer 154B; “CError1′” and CError2′”for multiplexer 154C; and “DError1′” and DError2′” for multiplexer154D), if any, are output from the multiplexers.

To comprehend the operation of the error detection circuit it should beunderstood that each one of the IDIC1 102 and IDIC2 124 includes Nboards corresponding with N separations, and that each board isassociated with a given slot. For instance, referring to the upper lefthand corner of FIG. 6, the first of four IDIC1 boards corresponds with“Slot 6 P2A3” and the first of four IDIC2 124 boards corresponds with“Slot 7 P2A3.” As contemplated by the exemplary implementation of FIG.6, when Gselect2 is high, then errors associated with IDIC1 may be“seen” at either the AError′ output (in the form of AError1′), theBError′ output (in the form of BError1′), the CError′ output (in theform of CError1′), or the DError′ output (in the form of DError1′). WhenGselect goes low, then errors associated with IDIC2 may be seen ateither the AError′ output (in the form of AError2′), the BError′ output(in the form of Berror2′), the CError′ output (in the form of Cerror2′),or the DError′ output (in the form of Derror2′). It should be noted thatthe error signals for all of the separations are visible to the MIOP 110(FIG. 3), and that each error signal provides the MIOP with anindication of the existence of an implementation error between the DFEand the image path or print engine. An implementation error might relateto the proper placement or operation of one of the IDIC cards in itsintended slot. Thus, for instance, if GSelect2 were low and AError2′ wasdetected by the MIOP, then it would follow that an error (relating to,for instance, faulty board placement) exists relative to the slot forthe first board of IDIC2 124.

In view of the above description, many features of the disclosedembodiments should now appear:

-   -   The capability to select among multiple “in-place” DFEs permits        the owner of a single print engine to fully and safely exploit        several printing applications. For instance, in one        implementation the owner might be provided the opportunity to        obtain a graphics application in one mode of operation, and a        standard color printing application in another. The fact that        the DFEs are in-place ensures that damage resulting from        repeated insertion and removal of related components is        minimized.    -   The switching aspect of the selection network can be constructed        from a simple, yet effective arrangement of logical components.        By using sets of readily available digital gates (such as OR or        NOR gates), cost can be minimized and scalability (corresponding        with the number separations to be employed) easily achieved.        Also, the design of the switching aspect makes it very easy to        switch between DFEs by simply altering the state of a first        select signal. Configuring the digital gates in a programmable        gate array can further optimize cost and convenience.    -   The manner in which the DFEs can be configured with the image        path also promotes scalability. In particular, since the IDIC,        CPM and RIM boards share the same image date interface bus,        multiple IDIC boards can be used in the image path without        significantly altering system architecture.    -   Implementation errors among the multiple DFEs and the image path        can be readily detected through use of a simple, yet effective        error detection circuit. In one example of operation, a set of        multiplexers, working in conjunction with the MIOP, can be used        to ensure, among other things, that all components of the system        (including DFEs and IDICs) are properly installed.

The claims, as originally presented and as they may be amended,encompass variations, alternatives, modifications, improvements,equivalents, and substantial equivalents of the embodiments andteachings disclosed herein, including those that are presentlyunforeseen or unappreciated, and that, for example, may arise fromapplicants/patentees and others.

1. A printing system for producing prints from a print job, comprising:a first digital front end capable of decomposing the print job; a seconddigital front end capable of decomposing the print job; an image path,communicating selectively with said first digital front end and saidsecond digital front end, for receiving a decomposed print job from saidfirst digital front end when said first digital front end and said imagepath are configured in a first mode, and for receiving a decomposedprint job from said second digital front end when said second digitalfront end and said image path are configured in a second mode; and aselection system for disposing either said first digital front end andsaid image path in the first mode, or said second digital front end andsaid image path in the second mode, wherein said selection systemincludes a first logical gate and a second logical gate, and whereinsaid first digital front end and said image path are disposed in thefirst mode when a first signal is output from said first logical gate,and said second digital front end and said image path are disposed inthe second mode when a second signal is output from said second logicalgate.
 2. The printing system of claim 1, in which a select signal,changeable between one of a first magnitude and a second magnitude, isinput simultaneously to each one of said first logical gate and saidsecond logical gate, wherein the respective outputs of said first andsecond logical gates change as a response to a change in the selectsignal between the first magnitude and the second magnitude.
 3. Theprinting system of claim 2, further comprising a user interface adaptedto change the magnitude of the select signal in response to user input.4. The printing system of claim 1, wherein (a) said selection systemincludes a third logical gate and a fourth logical gate, (b) said firstand second logical gates correspond with a first color separation, and(c) said third and fourth logical gates correspond with a second colorseparation.
 5. The printing system of claim 4, further comprising alogical gate array, wherein said first, second, third and fourth gatesare part of said logical gate array.
 6. The printing system of claim 1,wherein (a) said image path includes a first image data interface cardand a second image data interface card, (b) said first image datainterface card is corresponded with said first digital front end whensaid first digital front end and said image path are configured in thefirst mode, and (c) said second image data interface card iscorresponded with said second digital front end when said second digitalfront end and said image path are configured in the second mode.
 7. Theprinting system of claim 6, further comprising an image data interfacebus, wherein each one of said first image data interface card and saidsecond image data interface card selectively communicate with said imagedata interface bus.
 8. The printing system of claim 1, wherein saidselection system includes an error correction subsystem for testing forand detecting of implementation errors among said first digital frontend, said second digital front end, and said image path.
 9. The printingsystem of claim 8, wherein said error correction subsystem includes oneor more multiplexers, and wherein the output of said one or moremultiplexers provides information about at least one of theimplementation errors among said first digital front end, said seconddigital front end, and said image path.
 10. The printing system of claim9, in which the printing system is a color printing system processingthe print job in N separations, wherein said error correction subsystemcomprises N multiplexers.
 11. The system of claim 1, wherein the firstdigital front end comprises a graphics application.
 12. The system ofclaim 1, wherein the first digital front end comprises a standard colorprinting application.
 13. The system of claim 1, wherein the firstdigital front end comprises a standard color printing application andthe second digital front end comprises a graphics application.
 14. Thesystem of claim 1, wherein at least one of the first logical gate andthe second logical gates are of at least one of AND, OR, NOR gates. 15.A print control system for use with a print engine, comprising: a firstcontrol subsystem for decomposing a first job to obtain a first set ofprint-related information; a second control subsystem for decomposing asecond job to obtain a second set of print-related information; and aswitching system communicating selectively with said first controlsubsystem and said second control system; said switching system beingdisposed in a first switching state at a first time to direct the firstset of print-related information from said first control subsystem tothe print engine, and being disposed in a second switching state at asecond time to direct the second set of print-related information fromsaid second control subsystem to the print engine, wherein the switchingsystem includes a first logical gate and a second logical gate, andwherein said switching system is disposed on the first switching statewhen a first signal is output from the first logical gate, and saidswitching system is disposed in the second switching state when a secondsignal is output from second logical gate.
 16. The print control systemof claim 15, in which a select signal, changeable between a firstmagnitude and a second magnitude, is input simultaneously to each one ofsaid first logical gate and said second logical gate, wherein therespective outputs of said first and second logical gates change as aresponse to a change in the select signal between the first magnitudeand the second magnitude.
 17. The print control system of claim 15,wherein (a) said switching system includes a third logical gate and afourth logical gate, (b) said first and second logical gates correspondwith a first color separation, and (c) said third and fourth logicalgates correspond with a second color separation.
 18. The print controlsystem of claim 15, wherein the first digital front end comprises one ofa standard color printing application and a graphics application.
 19. Amethod for producing prints from a print job, comprising: configuring afirst digital front end, a second digital front end and image path insuch a way that the image path receives a rasterized print job from thefirst digital front end when the first digital front end and the imagepath are configured in a first mode, and that the image path receives arasterized print job from the second digital front end when the seconddigital front end and the image path are configured in a second mode,wherein the configuring includes configuring a first logical gate and asecond logical gate in such a way that the first digital front end andthe image path are disposed in the first mode when a first signal isoutput from the first logical gate, and the second digital front end andthe image path are disposed in the second mode when a second signal isoutput from second logical gate; and disposing either the first digitalfront end and the image path in the first mode, or the second digitalfront end and the image path in the second mode.
 20. The method of claim19, wherein said configuring includes providing third and fourth logicalgates, further comprising corresponding the first and second logicalgates with a first color separation and corresponding the third andfourth logical gates with a second color separation.
 21. The method ofclaim 19, further comprising detecting implementation errors among thefirst digital front end, the second digital front end, and the imagepath.